It is well known that streamlining the back of a vehicle such as a trailer truck will reduce the aerodynamic resistance of a moving vehicle and thus save fuel. However, attaching streamlining devices to the rear of the truck inhibits opening the rear doors. To open the rear doors the driver had to either detach, unlatch, fold, deflate or activate hydraulic, pneumatic, electric or spring assist devices or perform any combination thereof before or while opening the rear doors. The device described herein becomes a pair of highly aerodynamic curved airfoils when the doors are closed and moves flush against the sides of the truck when the doors are opened. The driver simply opens or closes the doors to change flat sheets into curved airfoils without the use of any hydraulic, pneumatic, electrical or spring assist eliminating the initial cost, maintenance expenses, and weight related of such assist devices.